gkenyon:

Nope.


What are you getting at?


This particular example hasn't been stated as low fault level, so we must assume 16 kA (and 0.35 omega Ze) - of course could be higher fault level if larger supply than the standard 100 A.


As I stated, it's not the fault level at the end of the cable that's important, it's the fault level at the start of the cable.


However, no para in EIDG still says the same thing.


I'm sure someone will point out that "in many houses the fault level is below 3 kA" - well, it's not in mine, which is often over 6 kA, and I'm over half way down our street from the substation.

Specifically, I'm asking whether Zs can still be used to determine the level of fault current to use in the adiabatic equation, as was suggested in section 8.4.2 of the EIDG (2015), for low levels of fault current (defined in that edn as being below 3kA), or whether that method has now been removed from the 18th edn. If it has, so be it, and it's a case of using the energy let-through data from the manufacturer, or the BS. I don't have the book yet, so that's all I was asking: has it been removed?


If it has been removed, that begs the question then of what protective device fault level should be used if a measured value indicates a low fault level. For example, if a 100A single phase domestic supply has measured loop impedance values at the origin of 1200amps L-N and L-E (just examples), and cb's to BS EN 60898 are used, what device kA fault level should be used, to then determine the respective kA2S value for that fault level to use in the adiabatic equation (would it be minimum 6kA fault level, to comply with the 16kA rating of CU's to BS EN 61439 on a 100A supply)? 


F

gkenyon:

Nope.


What are you getting at?


This particular example hasn't been stated as low fault level, so we must assume 16 kA (and 0.35 omega Ze) - of course could be higher fault level if larger supply than the standard 100 A.


As I stated, it's not the fault level at the end of the cable that's important, it's the fault level at the start of the cable.


However, no para in EIDG still says the same thing.


I'm sure someone will point out that "in many houses the fault level is below 3 kA" - well, it's not in mine, which is often over 6 kA, and I'm over half way down our street from the substation.

Specifically, I'm asking whether Zs can still be used to determine the level of fault current to use in the adiabatic equation, as was suggested in section 8.4.2 of the EIDG (2015), for low levels of fault current (defined in that edn as being below 3kA), or whether that method has now been removed from the 18th edn. If it has, so be it, and it's a case of using the energy let-through data from the manufacturer, or the BS. I don't have the book yet, so that's all I was asking: has it been removed?


If it has been removed, that begs the question then of what protective device fault level should be used if a measured value indicates a low fault level. For example, if a 100A single phase domestic supply has measured loop impedance values at the origin of 1200amps L-N and L-E (just examples), and cb's to BS EN 60898 are used, what device kA fault level should be used, to then determine the respective kA2S value for that fault level to use in the adiabatic equation (would it be minimum 6kA fault level, to comply with the 16kA rating of CU's to BS EN 61439 on a 100A supply)? 


F